Phenolic Content and Antioxidant Activities of Fruit Extracts of &lt;i&gt;Morus nigra&lt;/i&gt; L (Moraceae) from Southeast Serbia

Ss Mitiæ,Ds Dimitrijeviæ,Da Kostiæ,Gs Stojanoviæ,Mn Mitiæ,Av Živanoviæ

doi:10.4314/tjpr.v12i1.17

Abstract

Purpose: To evaluate the content of phenolic compounds (flavonoids and anthocyanins) of Morus nigra L. fruit (black mulberry) as well as the antioxidant activities of its extracts.Methods: The contents of phenols, flavonoids and anthocyanins of the ethanol, ethanol-water (50/50,v/v) and water extracts of black mullbery were determined using spectrophotometric methods. Antioxidant assay was based on the measurement of 2,2-diphenyl-1-picrylhydrazyl (DPPH) absorbance at 517 nm caused by the reaction of DPPH with the test sample, and also on the measurement of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) absorbance at 734 nm caused by the reaction of ABTS with the test sample.Results: Spectrophotometric analysis indicates that the content of total phenol compounds in the extracts varied from 90.26 to 118.84 mg GAE/100 g of fresh mulberry fruit. The content of anthocyanins ranged from 114.83 to 128.68 mg of cyanidin-3-O-glucoside/100 g of fresh fruit (ff). The fruit extract (0.1 ml) showed high antioxidant activity with DPPH radical transformation value of 71.41 % in ethanol-water (50/50, v/v)) extract and good antioxidant activity (relative to trolox equivalent as standard) with ABTS of 55.43 % in the water extract.Conclusion: The high phenolic content and high antioxidant activity of black mulberry from Southeast Serbia underline the nutritive and phytomedicinal potentials of the fruit. Further studies are, however,required before the fruit extract can be exploited in the production of health foods and as an antioxidant carrier in the food and pharmaceutical industries.Keywords: Morus nigra L., Natural phenolics, Antioxidant activity, Southeast Serbia

Highlights

Free radicals are atoms or molecules containing unpaired electrons
The antioxidant assay is based on the measurement of the loss of colour of DPPH solution by change of absorbance at 517 nm caused by the reaction of DPPH with the test sample
A high degree of correlation exists between monmeric anthocyanin content and antioxidant activity based on ABTS assay (0.9993) and between the content of polymeric color and antioxidant activity based on DPPH assay (0.9137)

Summary

INTRODUCTION

Free radicals are atoms or molecules containing unpaired electrons. The chain reaction caused by free radicals can lead to cross-linking of atomic structures. Total monomeric anthocyanin content of the plant extracts was determined using pH-. Differential method is based on the reaction producing oxonium forms This alloved accurate and rapid measurement of total monomeric anthocyanins. In this method, 1 ml of the liquid black mulberry extract prepared by a previously described procedure, was poured into two separate 10 ml volumetric flasks. The antioxidant assay is based on the measurement of the loss of colour of DPPH solution by change of absorbance at 517 nm caused by the reaction of DPPH with the test sample. ABTS radical cation was produced by reaction of ABTS stock solution with 2.4 ·10-3 mol L-1 potassium persulfate and allowing the mixture to stand in the dark at room temperature for 12 - 16 h before use. Significant differences among mean values, where applicable, were determined by one-way analysis of variance (ANOVA), while differences among samples were determined by Duncan's Multiple Range test using Statistical Analysis System (SAS 1999) software [21]

RESULTS

DISCUSSION

CONCLUSION